One who, while dressed in brightly coloured silly clothes and an inadequate helmet, rides a (racing) bicycle (often in heavy urban or rush-hour traffic) at high speed and without signls, as if they have no interest in their own safety or that of others, and genuinely wish to die as soon as possible in a multi-vehicle collision of their own making. They invariably look offended if forced to give way to cars, whatever the circumstances. See also kamikaze.

"I nearly got T-boned by a Suicyclist running a red light in my way in this morning".